Insmed (INSM) legal chief sells 4,109 shares to cover RSU taxes

Rhea-AI Filing Summary

INSMED Inc Chief Legal Officer Michael Alexander Smith reported an open-market sale of 4,109 shares of common stock at an average price of $116.18 per share. According to the filing, the shares were sold to satisfy tax withholding obligations upon the vesting of Restricted Stock Units and to cover related broker fees. Following this tax-related sale, Smith directly holds 47,762 shares of INSMED common stock.

Insider Trade Summary

Net Seller: 4,109 shares ($477,384)

Net Sell 1 txn

Insider Smith Michael Alexander

Role Chief Legal Officer

Sold 4,109 shs ($477K)

Type	Security	Shares	Price	Value
Sale	Common Stock	4,109	$116.18	$477K

Holdings After Transaction: Common Stock — 47,762 shares (Direct, null)

Footnotes (1)

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Key Figures

Shares sold: 4,109 shares Sale price per share: $116.18 per share Shares held after transaction: 47,762 shares

3 metrics

Shares sold 4,109 shares Open-market sale on 2026-05-13 to cover RSU taxes

Sale price per share <money>$116.18</money> per share Average price for 4,109 INSMED common shares sold

Shares held after transaction 47,762 shares Direct ownership following the reported sale

Key Terms

Restricted Stock Units, open-market sale, tax withholding obligations

3 terms

Restricted Stock Units financial

"upon the vesting of Restricted Stock Units and to cover related broker fees"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

open-market sale financial

"transaction_action": "open-market sale""

An open-market sale is when a shareholder sells existing shares directly on a public exchange to any willing buyer, rather than through a private deal. Think of it like putting goods on a busy market stall where price is set by supply and demand; for investors it matters because such sales increase available supply, can put short-term downward pressure on the stock price, and signal changes in liquidity or investor confidence.

tax withholding obligations financial

"Shares sold to satisfy tax withholding obligations upon the vesting"

Form 4 Insider Transactions: What Each Field Means →

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Smith Michael Alexander

(Last) (First) (Middle)

700 US HIGHWAY 202/206

(Street)

BRIDGEWATER NEW JERSEY 08807

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
INSMED Inc [ INSM ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Legal Officer

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
05/13/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	05/13/2026		S(1)		4,109	D	$116.18	47,762	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. Shares sold to satisfy tax withholding obligations upon the vesting of Restricted Stock Units and to cover related broker fees.

Remarks:

	/s/ Michael A. Smith	05/15/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)

FAQ

What insider transaction did INSM Chief Legal Officer Michael Smith report?

Michael Alexander Smith reported an open-market sale of 4,109 INSMED Inc common shares. The filing notes the shares were sold to cover tax withholding obligations from Restricted Stock Units vesting and related broker fees, rather than as a discretionary portfolio sale.

At what price did Michael Smith sell his INSMED (INSM) shares?

The reported sale of 4,109 INSMED common shares was executed at an average price of $116.18 per share. This price reflects the transaction used to satisfy tax withholding obligations tied to Restricted Stock Unit vesting and associated broker fees, as disclosed in the filing footnote.

How many INSMED shares does Michael Smith hold after this Form 4 sale?

After the reported transaction, Michael Alexander Smith directly owns 47,762 INSMED common shares. The filing characterizes the 4,109-share sale as covering tax withholding from Restricted Stock Units vesting, so his remaining holdings still represent a significantly larger position than the shares disposed.

Why did INSMED executive Michael Smith sell 4,109 shares of INSM stock?

The filing states the 4,109 INSMED shares were sold to satisfy tax withholding obligations upon the vesting of Restricted Stock Units and to pay related broker fees. This indicates a tax-related, mechanistic transaction rather than a discretionary open-market sale for investment reasons.

What role does Michael Smith hold at INSMED Inc related to this Form 4?

Michael Alexander Smith serves as Chief Legal Officer at INSMED Inc and is the reporting person on this Form 4. His position as an executive officer requires disclosure of transactions like this tax-related sale of Restricted Stock Unit shares in the company’s common stock.